The present invention relates to test instrumentation generally and more specifically to instrumentation for testing digital communication networks.
Digital communication networks utilize increasingly higher frequency channels multiplexed onto increasingly higher frequency carriers, including optical carriers. Most consumers do not need the entire bandwidth of a high frequency channel. A high frequency channel may be time multiplexed to contain many lower frequency channels, each lower frequency channel providing service to a consumer. Before a lower frequency channel may be tested, it is generally received and demultiplexed from the high frequency channel. The lower frequency channel may then be tested in a variety of ways, involving various terminations and signal paths. Channel terminations may include terminating the channel in a characteristic impedance, passing the channel through to its destination, looping the channel onto another channel of the same characteristic, or multiplexing the channel onto a carrier.
The net result is that telecommunication test instruments manipulate potentially several hundred low frequency channels through several possible test paths, and apply several different test conditions. Test instruments capable of testing high frequency digital communication channels, especially electrical test ports of optical fibers such as an STS-1 channel, are typically bench-top units. The size, weight and power consumption of these units nearly prohibits testing STS-1 channels in the field.
Testing of lower frequency transmission services on higher frequency transmission networks can become very complicated if the testing configurations have to be made manually. A menu driven test system, currently available in prior art bench-top and hand-held units, may simplify test setup by configuring a device to a selected condition. Although a graphical presentation of the final test configuration may clarify which test configuration has been chosen, a long menu-driven setup process can still lead to incorrect test configurations and invalid test results.
Additionally, menu-driven test systems typically require a user to remember several mnemonics, or alternatively, to read the menu commands off of a separate, printed index key. A forgotten command or index key may result in inability to perform the desired test.